Release superseded assistant text from live paginated history (#58751)

## Why

Live paginated history retains completed assistant text even when summaries only need the latest message. Release older text for threads with persisted history while preserving full resume responses.

## What changed

- Evict superseded assistant text from live turn state while preserving corrected items and the latest assistant message.
- Restore evicted text for full resume responses from prepared history pages, fetching remaining items by ID in bounded batches. Return an error if saved text is missing.
- Only load the active turn when it belongs in the requested initial page, and use the item ID index for targeted history reads.

## Testing

Add reducer coverage for text eviction and corrected messages. Extend running-thread resume coverage to compare full and summary items with live notifications, exercise restoration when the prepared page lacks the active turn, and check missing-text errors.

GitOrigin-RevId: 3229c0cea820f117dc6331312f1e6056a8d1d52c

codex-rs/thread-store/src/local/thread_history/segment_paging.rs

@@ -294,10 +294,10 @@ pub(super) async fn page_item_rows(
 SELECT turn_id, item_id, rollout_ordinal, updated_at_ordinal, created_at_ms, started_at_ms, completed_at_ms, item_json
 FROM thread_items"#,
         );
-        if params.turn_id.is_some()
-            && params.item_ids.is_none()
-            && params.after_updated_at_ordinal.is_none()
-        {
+        if params.item_ids.is_some() {
+            // Seek each requested ID instead of scanning the turn in rollout order.
+            query.push(" INDEXED BY sqlite_autoindex_thread_items_1");
+        } else if params.turn_id.is_some() && params.after_updated_at_ordinal.is_none() {
             // A thread-wide index can scan earlier turns when a turn's final page is underfilled.
             query.push(" INDEXED BY idx_thread_items_by_turn_page");
         }